A Whale of a Waterslide

Here's your nightly math! Just 5 quick minutes of number fun for kids and parents at home. Read a cool fun fact, followed by math riddles at different levels so everyone can jump in. Your kids will love you for it.

A Whale of a Waterslide

The waterslide is one of the most exciting summer treats: fast turns, jets of water shooting at you, giant splash at the bottom. Now imagine if the whole waterslide were alive! Scientists actually caught photos of a dolphin taking waterslide rides down the back of a whale. We hope the whale didn’t mind: humpback whales weigh almost 80,000 pounds, while a bottlenose dolphin weighs less than 1/100th of that. Never mind that those whales grow to 50 feet or longer…these dolphins reach only 10-12 feet at most. It all worked out, giving that playful dolphin one more reason to smile.

Wee ones: One dolphin took 6 rides in a row. Flap your arms like flippers, and hop 6 times!

Little kids: If the dolphin slides down the right side of the whale, then the left side, then the right side again to repeat…after 5 turns, how many times does it slide to the right? Bonus: If it takes the dolphin 10 seconds to get on top of the whale and then 4 seconds to slide down, how long does each ride take?

Big kids: If the 12-foot dolphin is a whole 39 feet shorter than the whale, how long is the whale? Bonus: If a 79,000-pound whale weighs exactly 100 times the dolphin, how much does the dolphin weigh? (Hint if needed: To start, what if it weighed 10 times as much?)

The sky’s the limit: Back to that sliding game…if the dolphin slides down the right side, then the left side, then the left again, then repeats, which side will it pick for the 123rd turn?

Answers:Wee ones: Count your hops: 1, 2, 3, 4, 5, 6.

Little kids: 3 times to the right (turns 1, 3 and 5). Bonus: 14 seconds.

The sky’s the limit: The left side. 123 is a multiple of 3, and all multiples of 3 will be the same. You can tell whether any number is divisible by 3 by adding up its digits: if they add up to a multiple of 3, then so is the number. In this case, the digits add up to 1+2+3=6!

About the Author

Laura Bilodeau Overdeck is founder and president of Bedtime Math Foundation. Her goal is to make math as playful for kids as it was for her when she was a child. Her mom had Laura baking before she could walk, and her dad had her using power tools at a very unsafe age, measuring lengths, widths and angles in the process. Armed with this early love of numbers, Laura went on to get a BA in astrophysics from Princeton University, and an MBA from the Wharton School of Business; she continues to star-gaze today. Laura’s other interests include her three lively children, chocolate, extreme vehicles, and Lego Mindstorms.